An assessment of dust generation from ores

Dust from mining activities is produced from several unit operations and is often a serious problem to the industry, due to the influence it can have on human health and the safety record and productivity of a mine. So far, legislative parties and the industry have approached dust as an issue that needs to be controlled, only when a mining operation or process generates undesirable particulates. Nevertheless, new legislation and standards, such as the EU IPPC directive (Integrated Pollution Prevention and Control) and air quality strategies aim to drive mining companies to incorporate dust assessment planning that will be implemented through the whole life cycle of the mine. Mitigation and monitoring practices as well as health surveillance programs will need to be clearly defined. This project’s purpose is to understand how mining processes and in particular how the mechanisms inherent within common unit operations (i.e transfer processes using haulage roads or conveyor belts, the tipping, loading and stockpiling process, the screening process etc) result in the generation of dust. If the operation of unit operations could by optimized to produce less dust, then a “fit-for-purpose” strategy for dust minimisation could be developed to follow exploitation, processing and production demand. The literature on dust from mining operations identified that generation of fines/dust occurs due to the presence of the mechanisms of abrasion and impact. Based on this logic, an experimental methodology was developed, which aimed to assess how dust was generated for each different mechanism and for a variety of ores of different mineralogy. Five different ores were tested, a limestone, talc, an iron ore, a lamproite and a copper ore and the same experimental methodology was followed for each. Experimentation using the HSE-WSL tumbling mill test determined that under the effect of abrasion, ores yielded higher dustiness values during longer tumbling times, whilst parameters such as the sample mass and the particle size distribution of the feed sample could also influence the dust generation patterns. The findings of the computational modelling (discreet element modelling) and experimentation (high speed video recording) suggested that control and optimisation of operational parameters (e.g mill velocity, or tumbling time) within processes that involve abrasion, such as the use of conveyor belts, mills, and screens could minimise the potential of dust generation by this mechanism. The use of a novel impact test determined a positive relationship between the energy input and the particle size distributions of the broken particles, as well as the accumulation of fine particulates in the range of dust (<75μm). Also an increase in the bulk volume of ores resulted in larger quantities of fine particulates. These observations suggest that it is possible to reduce dust in processes that involve drop from heights and impaction (i.e transfer points in conveyor belts, tipping, loading) by adjusting the energy input and the bulk volume of ore at impact to as low a level possible. Particle size analysis of the produced dust fractions were found to be material dependent and varied considerably for the different ores. Almost all materials produced significant amounts of ultra fine particles below 10μm and 2.5μm, both under impact and abrasion, which reveals the potential adverse impacts to the environment and human health. Quantitative mineralogical analysis using the mineral liberation analyser determined that the dust fraction presents a different composition to that of the ore. Comparison of the results collected for the five different ores using the HSE-WSL mill and the impact test identified that certain materials yielded high dust levels under abrasion and low under impact. Therefore it would be expected that dust control approaches for such materials would differ according to the mechanisms of the involved process and the mineralogy of the sample. According to the findings of this study a reduction in dust produced from mining unit operations could be possible by optimising the involved processes either by altering their operating parameters (drop height during tipping, velocity of conveyor belt) or by optimising the design of processes so as to reduce abrasion or impact. New legislation such as the EU IPPC directive has already started considering such an approach as important, and newly developed Best Available Techniques documents refer to this as the primary step companies should follow to minimise dust. Additional advantages of this approach are that it can reduce cost for dust control by making use of less conventional mitigation practices, and in the long term it could also minimise the utilization of energy and water going to suppression, extraction and dust collection systems. In certain cases the proposed route could also optimise the production chain, especially where the generation of fines is undesirable (e.g iron ore processing or aggregates production)

An assessment of dust generation from ores

Dust from mining activities is produced from several unit operations and is often a serious problem to the industry, due to the influence it can have on human health and the safety record and productivity of a mine. So far, legislative parties and the industry have approached dust as an issue that needs to be controlled, only when a mining operation or process generates undesirable particulates. Nevertheless, new legislation and standards, such as the EU IPPC directive (Integrated Pollution Prevention and Control) and air quality strategies aim to drive mining companies to incorporate dust assessment planning that will be implemented through the whole life cycle of the mine. Mitigation and monitoring practices as well as health surveillance programs will need to be clearly defined. This project’s purpose is to understand how mining processes and in particular how the mechanisms inherent within common unit operations (i.e transfer processes using haulage roads or conveyor belts, the tipping, loading and stockpiling process, the screening process etc) result in the generation of dust. If the operation of unit operations could by optimized to produce less dust, then a “fit-for-purpose” strategy for dust minimisation could be developed to follow exploitation, processing and production demand. The literature on dust from mining operations identified that generation of fines/dust occurs due to the presence of the mechanisms of abrasion and impact. Based on this logic, an experimental methodology was developed, which aimed to assess how dust was generated for each different mechanism and for a variety of ores of different mineralogy. Five different ores were tested, a limestone, talc, an iron ore, a lamproite and a copper ore and the same experimental methodology was followed for each. Experimentation using the HSE-WSL tumbling mill test determined that under the effect of abrasion, ores yielded higher dustiness values during longer tumbling times, whilst parameters such as the sample mass and the particle size distribution of the feed sample could also influence the dust generation patterns. The findings of the computational modelling (discreet element modelling) and experimentation (high speed video recording) suggested that control and optimisation of operational parameters (e.g mill velocity, or tumbling time) within processes that involve abrasion, such as the use of conveyor belts, mills, and screens could minimise the potential of dust generation by this mechanism. The use of a novel impact test determined a positive relationship between the energy input and the particle size distributions of the broken particles, as well as the accumulation of fine particulates in the range of dust (<75μm). Also an increase in the bulk volume of ores resulted in larger quantities of fine particulates. These observations suggest that it is possible to reduce dust in processes that involve drop from heights and impaction (i.e transfer points in conveyor belts, tipping, loading) by adjusting the energy input and the bulk volume of ore at impact to as low a level possible. Particle size analysis of the produced dust fractions were found to be material dependent and varied considerably for the different ores. Almost all materials produced significant amounts of ultra fine particles below 10μm and 2.5μm, both under impact and abrasion, which reveals the potential adverse impacts to the environment and human health. Quantitative mineralogical analysis using the mineral liberation analyser determined that the dust fraction presents a different composition to that of the ore. Comparison of the results collected for the five different ores using the HSE-WSL mill and the impact test identified that certain materials yielded high dust levels under abrasion and low under impact. Therefore it would be expected that dust control approaches for such materials would differ according to the mechanisms of the involved process and the mineralogy of the sample. According to the findings of this study a reduction in dust produced from mining unit operations could be possible by optimising the involved processes either by altering their operating parameters (drop height during tipping, velocity of conveyor belt) or by optimising the design of processes so as to reduce abrasion or impact. New legislation such as the EU IPPC directive has already started considering such an approach as important, and newly developed Best Available Techniques documents refer to this as the primary step companies should follow to minimise dust. Additional advantages of this approach are that it can reduce cost for dust control by making use of less conventional mitigation practices, and in the long term it could also minimise the utilization of energy and water going to suppression, extraction and dust collection systems. In certain cases the proposed route could also optimise the production chain, especially where the generation of fines is undesirable (e.g iron ore processing or aggregates production)

Mapping the global flow of tungsten to identify key material efficiency and supply security opportunities

Tungsten is an economically important metal with diverse applications ranging from wear resistant cutting tools to its use in specialized steels and alloys. Concerns about its supply security have been raised by various studies in literature, mostly due to trade disputes arising from supply concentration and exports restrictions in China and its lack of viable substitutes. Although tungsten material flows have been analysed for specific regions, a global mass flow analysis of tungsten is still missing in literature and its global supply chain remains opaque for industry outsiders. The objective of this paper is to create a map of global tungsten flows to highlight and discuss key material efficiency (i.e. using less of a material to make a product or supply a service, or reducing the material entering production but ending up in waste) and supply security opportunities along tungsten‘s supply chain that could be incorporated into the planning and prioritization of future supply security strategies. The results indicate the existence of various intervention alternatives that could help to broaden the supply base and improve the overall material efficiency of the system. In particular, future policy and research and development (R&D) efforts to improve tungsten‘s material efficiency should focus on minimizing tungsten losses as fine particles during beneficiation and extraction (current global losses estimated at 10–40%), as well as on evaluating alternatives to improve recycling collection systems and technologies, which could lead to 17–45% more tungsten discards being recycled into new products.E. Petavratzi, T.J. Brown and A.G. Gunn publish with the permission of the Executive Director of the British Geological Survey. David R. Leal-Ayala and Julian M. Allwood were supported by the UK Engineering and Physical Sciences Research Council (EPSRC) through a Leadership fellowship (reference EP/G007217/1) and a research grant awarded to the UK Indemand Centre (reference EP/K011774/1). We thank Michael Dornhofer, Felix Gaul and Markus Ettl from Wolfram Bergbau und Hütten AG for their generous contributions to the paper.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S0921344915300367

Decarbonising the automotive sector: a primary raw material perspective on targets and timescales

Decarbonisation of the automotive sector will require increased amounts of raw materials such as lithium, cobalt, nickel and rare earth elements. Consequently, it is crucial to assess whether supply will be able to meet forecast demand within the required timescale. The automotive sector relies on complex global supply chains comprising four tiers. We have developed an integrated timeline from tier 4 (supply of raw materials) through to tier 1, the production of electric vehicles (EVs). Numerous factors, mainly economic, political, social and environmental, influence the duration of tier 4 leading to considerable variation between projects. However, our analysis demonstrates that it commonly takes more than 30 years from initial exploration to EV production. Tier 4, which is often neglected by the automotive industry, may account for 20 years of that period. This suggests that raw material supply is unlikely to match the projected demand from electrification of the automotive sector up to 2030. Reducing the duration of tier 4 will be difficult, although governments and industry can mitigate supply risks in various ways. These include multi-disciplinary international research across the supply chain and the transformation of research findings into policy and best practice. Supply chain convergence, with businesses across the supply chain working to develop long-term plans for secure and sustainable supply, will also be beneficial. In addition, global stakeholders should work together to resolve ESG challenges to supply. All these measures depend on the availability of researchers and industry personnel with appropriate skills and knowledge

A bottom-up building stock quantification methodology for construction minerals using Earth Observation. The case of Hanoi

Increasing demand for significant volumes of construction materials, especially sand for use in concrete, in rapidly developing urban environments is becoming a significant socio-economic and environmental issue. The consumption of concrete (comprised of sand, aggregates and cement) is especially concerning on a city level as vast volumes of materials are extracted within the urban hinterland, causing direct impacts locally and the potential for supply issues directly impacting city level metabolism. Excessive consumption and poor management of these materials make it increasingly hard for society to ensure new urban development and infrastructure projects, essential for maintaining the health of cities, meet sustainable development objectives. However, it is difficult to implement suitable resource management policies without first understanding how materials are produced and consumed at an appropriate spatial level. For many areas, especially on a city level, such data is absent, especially so for sand and aggregates which can further exacerbate these local supply issues and environmental impacts. This study attempts to address this data gap via combining earth observation datasets with estimates of materials contained within urban infrastructure (material intensities) to calculate the rapid increase of construction material stocks in Hanoi. Spatial data on buildings have been gathered using, producing, and collating a variety of spaceborne open-source datasets on built up areas (GlobalMLBuildingFootpint, World Settlement Footprint 3D, Open Street Map) and land use classification maps. Linking this spatial data with estimated quantities of sand, gravel, cement and concrete in typical buildings in Hanoi enables quantification of building stocks for a range of building types over a time series. The results show that for every new km2 of urban infrastructure approximately 520,000 tonnes of concrete, or 360,000 tonnes of sand, 580,000 tonnes of gravel and 115,000 tonnes of cement are required. If the Hanoi Masterplan is to be achieved by 2030, then the material demand is likely to be for 106 million tonnes of concrete or 73 million tonnes of sand, 118 million tonnes of gravel and 24 million tonnes of cement. These all exceed historical consumption trends and are far in excess of current extraction rates and therefore careful planning is required to ensure access to sustainable resources into the future

Fuelling the Foundation Industries: Discovering the Hidden Value of Mineral Waste in the UK

The Foundation Industries (FIs) (chemical, cement, ceramic, glass, metal, and paper sectors) are worth GBP 52 billion to the UK economy and produce 75% of its materials and 10% of its total CO2 emissions. The UK extractive industry annually supplies millions of tonnes of mineral products used in FI manufacturing processes. It is estimated that mineral extraction results in upwards of 50 million tonnes of mineral waste every year. In 2021, the British Geological Survey embarked on a series of visits to UK mineral operations to improve the understanding of mineral waste production, composition, and its potential for use. This has enabled the sharing of data and information on poorly understood stocks and flows of waste materials between different industries and led to potential new applications for use of mineral wastes in novel polymer coatings and investment casting

Understanding the spatial variation in lithium concentration of high Andean Salars using diagnostic factors

Salars (basins of internal drainage) in the “Lithium Triangle” countries (Argentina, Bolivia, Chile) hold >50 % of the global lithium resources within lithium-rich brines. Given the imperative for lithium production to enable the energy transition and that salars by their very nature are highly variable, so a framework to both characterise their differences as well as identifying their similarities would be beneficial to understanding their provenance and potential for exploitation. In this study, data for 29 salars based on environmental factors: rainfall, evaporation as well as their physical characteristic: pan size and basin size have been used to characterise them along with those describing their setting land-use/cover and geological outcrop. These parameters have been normalised by creating a ratio of the lithium concentration divided by the factor for each salar. Cross-correlation has been used to develop relationships between these normalised factors, combined with principal component analysis to identify clustering and to further characterise groupings of behaviours. Two such relationships emerge out of this process: regional and local. Regional covers factors such as elevation, precipitation, and evaporation; local includes size of watershed, salar nucleus, land cover and geological outcrop in the watershed. However, Salar de Atacama is identified as an outlier and so the transferability of the understanding of its provenance and operation must be treated with caution. Other salars could be added to the framework as more information becomes available. The methodology presented here could help exploration by characterising salars into categories as their smaller size may not necessarily mean lower lithium mass. Further, such a framework can inform policy decisions and instruments by recognising the complexity of salars combined with the need to understand the environmental impacts of brine extraction

Vietnam - Hanoi city material flows

This report describes the first phase of research for a minerals materials flow analysis in an Asian Megacity. This consists of a scoping study to assess the feasibility of conducting material flow analysis (MFA) for Hanoi, with a particular focus on assessing the availability of required data. The availability of data on the production, trade, consumption, and demand for constructionrelated mineral commodities at a national, regional and city level within Vietnam was assessed. Although current levels of publically available data are insufficient to allow a full MFA analysis we present the results obtained from a preliminary analysis of material supply and demand in Hanoi. Supply and demand scenarios up to 2030 for several commodities important for the construction sector have been evaluated. Recommendations are also made for future application of MFA in Hanoi. This research was supported by BGS NC-ODA grant NE/R000069/1 entitled Geoscience for Sustainable Futures. It was delivered via the BGS Asian Cities Official Development Assistance (ODA) Research Platform

Development of a compact excavator mounted dust suppression system

This paper reports on the investigation of an excavator mounted dust suppression system for demolition and construction activities. Ever increasing pressure is placed on contractors to improve their environmental performance, especially dust emissions. Current methods of dust suppression have been investigated and each of the methods has also been critically analysed to determine their advantages and disadvantages. The investigation also examined the requirements of such a system and a concept system proposal was produced. A working prototype has been constructed for a mini excavator complete with a hydraulic breaker. The proposed system was rigorously tested in various configurations to determine its efficiency and effectiveness in comparison with current suppression techniques. The resulting benefits such as the reduction of water usage and cost are highlighted